This invention relates to a method and device for use in the manufacture of cigarette filters. More particularly, this invention relates to a method and device for very high speed delivery of controlled amounts of a free-flowing material into discrete receiving spaces between individual filter plugs in partially-constructed cigarette filters. The device of this invention has a plurality of conveyance devices, each utilizing vacuum to rapidly and efficiently transfer and accurately place the free-flowing material into the discrete receiving spaces.
Some of the present devices used to transfer a free-flowing material into discrete spaces between filter plugs in cigarette filters are limited in operating speed due to the time required for the free-flowing material to free fall under the influence of gravity. For example, in Williamson, U.S. Pat. No. 3,312,152, powder is transferred from a hopper to a pocket under vacuum, but later, the powder free falls from that pocket into another pocket solely under the influence of gravity. Still later the powder again free falls from the later pocket into receiving spaces between filter plugs.
Other devices utilize vacuum but also are limited in the speeds they can operate due to the limited period of contact between a transferring receptacle and a receiving receptacle. For example, in Molins, U.S. Pat. No. 3,312,151, powdered filter material is transferred from a hopper to pockets under vacuum, and then from the pockets to receiving spaces between the filter plugs under vacuum. However, each pocket only registers with the receiving space at one point. The wheel must rotate slowly enough to allow a suitable period of contact between the transferring pocket and the receiving space.
It would be desirable to replace the present devices with devices utilizing vacuum at all stages of the transfer of the free-flowing material. Vacuum facilitates transfer of free-flowing material at a much more rapid rate than gravity alone. It would likewise be desirable to replace the present devices with devices utilizing periods of parallel travel between the transferring receptacles and the receiving receptacles. Such parallel travel extends the period of contact between the receptacles, thus expanding the time available for transfer of the free-flowing material while still facilitating a very rapid process. Such use of vacuum and parallel travel would enable a device to deliver a free-flowing material at a much more rapid rate than present devices.